Electronic assemblies contain various electronic components that are used in many applications. For example, electronic assemblies contain components that collectively function as switches or router-hubs in network systems. A standard Electronic Industries Association (EIA) 19" form-factor rack may be used to support a plurality of electronic assemblies.
FIG. 1a illustrates a conventional electronic assembly 50 including a chassis assembly 55 that encloses a motherboard 60, at least one daughter-card 65, a power supply 70, blowers 75, and other components. Ports 80 are attached to the daughter-card 65 and protrude through apertures in the rear panel 85 of the chassis assembly. The ports 80 serve as interfaces between external cable lines and the wiring boards 60 and 65 that support the electronic components in the electronic assembly 50.
One drawback of the conventional electronic assembly 50 is the number of ports 80 that can be positioned across the width of the electronic assembly 50 is limited by the 19" mounting rail width of the rack opening. The number of ports 80 in such an electronic assembly is typically limited to a small number, for example, six (6) ports with a 60-position D-sub miniature connectors. Therefore, a conventional electronic assembly is unable to implement a larger-size printed wiring board (PWB) which desirably could support additional ports.
Another drawback arises when the conventional electronic assembly 50 is mounted on a standard rack. Access to the ports 80 from the rear of the rack is difficult or not possible, particularly if the rear of the rack is placed against the wall or if the electronic assembly does not extend to the full depth of the rack. Additionally, from the front side of the rack, it is difficult to manually reach the ports 80 if they are located at the rear. As a result, it is difficult to install, disconnect, or adjust cables that interface with the ports 80.
Typically, all cables egress and air exhaust occur in the rear panel. This leads to limited access to cables and increased impedance to air exhaust. Moreover, cable egress from the chassis is not controlled adequately and minimum bend radii violations often result, affecting data integrity.
Additionally, in the conventional electronic assembly 50, the ports 80 are disposed at the rear panel 85 of the chassis assembly 55 and, therefore, prevent a straight front-to-back flow of cooling ambient air. Typically, such conventional apparatus requires the use of the pressurized air-flow system 75, such as blowers which are more complex in design, contain more parts and are less commercially available in large quantities, thereby leading to higher cost. These blowers also have a high-noise attribute and have a stronger airflow driving capability (which leads to a higher power consumption). The blowers permit air to flow in a serpentine fashion within the chassis assembly 55 to cool the components within the chassis assembly. The direction of the air flow may be illustrated by arrows 90. The air will then exit through a side panel 95 of the chassis assembly 55. However, the pressurized air-flow system 75 leads to additional cost, power requirements, and noise, and is generally less efficient at cooling. A further drawback in the above-mentioned approach is a daughter-card 65 portion adjacent to the rear panel 85 may not be reached by the air flow for proper cooling. Additionally, the airflow 90 is blocked by rack rails or rack components as the airflow exits the side panel 95.
FIG. 1b illustrates another conventional electronic assembly 96 including a chassis assembly 97 that requires internal cables 98 that are routed from leads 99 to the motherboard 60 and the rear panel 92. The requirement of routing internal cables 98 internally within the chassis assembly 97 leads to increased cost and assembly time. In addition, it is more difficult and costly to repair and service the internal cables 98.
In the conventional electronic assembly 96 of FIG. 1b, external cables exit the front panel 93. This configuration adds to difficulties in accessing other electronic equipment on the same rack, since the external cables from the front panel 93 may interfere or block the other rack equipment.
Therefore, there is a need for an improved electronic assembly that can support a greater number of ports, permit easier access for cable installation, removal or adjustment, and provide a more efficient air flow configuration. There is also a need for an improved electronic assembly that achieves the above advantages while remaining compatible with standard form-factor racks, which are typically deeper that they are wide, and in this configuration, integration of motherboard features and function allows for lower assembly and per-piece part cost.